Heat the oven to 325 F. Place a wire rack over a rimmed baking sheet. Spray the rack with cooking spray.

Arrange the tomatoes on the rack, cut sides up. Sprinkle the tomatoes with the salt, sugar and white pepper. Roast for 1 hour. Flip the tomatoes over and roast for another hour, or until the tomatoes are soft, wrinkly and have shrunken considerably in size.

While the tomatoes are roasting, in a medium bowl stir together the ricotta, basil, thyme and oregano. Set aside to allow the flavors to meld.